452 STEARINE (STEARIC ACID) In general stearine forms hard, opaque, white masses, somewhat greasy to the feel and soluble in alcohol, especially in the hot. Analysis of commercial stearines comprises principally the following : 1. Solidifying Point (Titer) .—This is determined by Dalican's method (see p. 418), the content of stearine being deduced by means of the corre- sponding table ; when, however, fatty acids alone are concerned, the number given in the table is multiplied by — (see p. 419). «/•-' 2. Acid, Saponification and Iodine Numbers.—By the methods given in the preceding chapter. The iodine number depends on the quantity of oleic acid (and maybe of iso-oleic acid) in the stearine and this may be calculated from the iodine number by means of the formula 0 = — x I, or 0 = i-ii x I, 90, where 0 = oleic acid sought I = iodine number of the stearine and 90 is the iodine number of pure oleic acid. 3. Detection of Various Extraneous Substances.—Commercial steariftes sometimes contain solid paraffin or ceresine, wool fat stearine, wax and carnauba wax. The presence of such substances may be suspected as a rule when the acid number of the stearine is less than 195, but may be proved definitely as follows : (a) A. few grams of the stearine are digested in the hot with 95% alcohol. If the substance does not dissolve completely, the liquid is allowed to cool and filtered and an examination made of the insoluble part. The latter may contain solid paraffin or ceresine, beeswax or carnauba wax, their presence being indicated by the melting point, the acid and saponification numbers, etc. (see articles on Paraffin Wax, Ceresine and Beeswax).1 (b) A quantity of the stearine is hydrolysed with alcoholic potash and the unsaponifiable substances extracted and examined by the methods indicated on p. 388 et seq. ; the presence of cholesterol will indicate the presence of wool fat stearine in the substance. If then it is necessary to determine the various acids composing a stearine (stearic, palmitic, oleic) and to test for stearolactone, the methods indicated in the preceding chapter (see pp. 384 and 383) may be followed. Finally, when the presence of lactones is excluded, that of neutral fat may be deduced from the ester number and may be confirmed by testing for glycerine (see p. 384). Commercial stearines usually solidify between 48 and 55° (liter), the value for saponification stearine being somewhat higher than that for distillation stearine. The acid number should "not be less than 195 : if it is less than this, the presence of neutral fats or extraneous substances is denoted. 1 The presence of carnauba wax may be recognised also from the fact that, besides lowering the acid and saponification numbers of the stearine, it raises the melting point considerably, 5% of carnauba wax being sufficient to raise the melting point of a stearine by 10°, fat.